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Hundreds of mini solar systems found in the Milky Way

THE Milky Way is brimming with small-scale solar system lookalikes. A haul of more than 300 planetary systems reminiscent of our own has been found in data collected by a NASA planet-hunter.

“The planets are small, they have circular orbits, their orbital planes are flat – it starts to look like home very quickly,” says Jason Rowe of the SETI Institute in Mountain View, California. But these planets are crowded much closer to their stars than the worlds in our solar system, adding a wrinkle to our theories of how planets form and evolve.

Rowe’s team analysed the first two years’ worth of data from the Kepler space telescope, which has identified hundreds of confirmed planets as well as thousands of planet candidates. They were able to show that 715 Kepler candidates are real planets. Of those worlds, 94 per cent are smaller than Neptune and they are spread across 340 multi-planet systems (arxiv.org/abs/1402.6534).

Most of these planets lie in the same flat plane around the equators of their host stars, like the planets in our solar system. But because the systems are so compact, only four of the 715 worlds are far enough from their stars to potentially host liquid water.

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A broken steering system forced the Kepler team to end its main mission last year, but many other exciting finds might still be hiding in Kepler’s collection, says Sara Seager at the Massachusetts Institute of Technology. “People think it’s over, it’s dead, there’s been a requiem. But Kepler lives on. This is a great example of that.”

This article appeared in print under the headline “Hundreds of mini solar systems found in our galaxy”